Overview- Today's lesson will provide the students with basic information about the Earth's magnetic field. The students will apply their knowledge of plate tectonics to explain what causes the Earth to have a magnetic field. Also, an article will be used to generate notes on magnetic stripping. These two comcepts will explain how H. Hess came up with his theroy of plate tectonics.
Instructional Objectives-
- The students will examine seafloor spreading and magnetic stripping to understand the evidence of H. Hess' theory of Plate Tectonics
- The students will identify Earth's magnetic poles and design a model to represent it.
Time (85 minutes) Activity 10 minutes
Ø Review key points from the last class. Key points are:
1. What is a convection current?
2. Why do they occur?
3. What effect do they have on Earth’s plates?
- Tell the students that today they are going to work with Harry Hess’s theory of plate tectonics and discover what causes the earth to have magnetic poles. They will be able to identity how the magnetic stripping was discovered in the Atlantic Ocean 30 minutes
Ø Read and discuss the article as a class to make an outline. I will be the facilitator for this lesson, so the students highlight and record the important information. (The article is advanced for their level.) By reading the article together and making an outline students will be able to highlight the important information. Outline will be created on an overhead and students will record it in their notebooks 25 minutes
- Open with "Everyone knows we can use compasses because the Earth is a magnet. Did you ever wonder why the Earth is a magnet? Today we'll see how geologists anwser that question based on what we already know about plate tectonics."
- The class will break up into groups of two. One member will get the materials needed - the iron shavings, paper, a magnet.
- The students will follow the directions on their handout to complete this activity.
- Students will create their own magnetic fields. Students will use iron shavings and magnetic bar to create a line of polarity.
-The students will observe the teacher demo of water swirling, make inferences and try to create a change in their magnetic fields. At the end of the activity, the teacher will inform the students that science does not have a definite explanation for the observation of reversed polarity in the magnetic stripping. Scientists believe that the chaotic motion of the Earth’s outer core causes a spontaneous flip of polarity for only a short amount of time. This short amount of time is very unstable and last only 7-15 years. 15 minutes Conclusion
-Review the main concepts of the day's lesson:
- H. Hess' evidence for plate tectonics is seafloor spreading
-This was discovered because magnectic stripping was observed at the Mid-Atlantic Ridge.
-What is magnetic stripping?
-What does this have to do with seafloor spreading?
- Why the Earth has a magnetic feild.
Ø Hand out homework and explain directions.
Ø Students may start homework if time permits Assessment-
- Complete homework handout on Magnetic stripping. Activity Materials-
Ø Overhead
Ø Iron shavings
Ø Paper
Ø water in a jar
Ø 14 bar magnets
Overview- Today's lesson will provide the students with basic information about the Earth's magnetic field. The students will apply their knowledge of plate tectonics to explain what causes the Earth to have a magnetic field. Also, an article will be used to generate notes on magnetic stripping. These two comcepts will explain how H. Hess came up with his theroy of plate tectonics.
Instructional Objectives-
- The students will examine seafloor spreading and magnetic stripping to understand the evidence of H. Hess' theory of Plate Tectonics
- The students will identify Earth's magnetic poles and design a model to represent it.
Time (85 minutes) Activity
10 minutes
Ø Review key points from the last class. Key points are:
1. What is a convection current?
2. Why do they occur?
3. What effect do they have on Earth’s plates?
- Tell the students that today they are going to work with Harry Hess’s theory of plate tectonics and discover what causes the earth to have magnetic poles. They will be able to identity how the magnetic stripping was discovered in the Atlantic Ocean
30 minutes
Ø Read and discuss the article as a class to make an outline. I will be the facilitator for this lesson, so the students highlight and record the important information. (The article is advanced for their level.) By reading the article together and making an outline students will be able to highlight the important information. Outline will be created on an overhead and students will record it in their notebooks
25 minutes
- Open with "Everyone knows we can use compasses because the Earth is a magnet. Did you ever wonder why the Earth is a magnet? Today we'll see how geologists anwser that question based on what we already know about plate tectonics."
- The class will break up into groups of two. One member will get the materials needed - the iron shavings, paper, a magnet.
- The students will follow the directions on their handout to complete this activity.
- Students will create their own magnetic fields. Students will use iron shavings and magnetic bar to create a line of polarity.
-The students will observe the teacher demo of water swirling, make inferences and try to create a change in their magnetic fields. At the end of the activity, the teacher will inform the students that science does not have a definite explanation for the observation of reversed polarity in the magnetic stripping. Scientists believe that the chaotic motion of the Earth’s outer core causes a spontaneous flip of polarity for only a short amount of time. This short amount of time is very unstable and last only 7-15 years.
15 minutes Conclusion
-Review the main concepts of the day's lesson:
- H. Hess' evidence for plate tectonics is seafloor spreading
-This was discovered because magnectic stripping was observed at the Mid-Atlantic Ridge.
-What is magnetic stripping?
-What does this have to do with seafloor spreading?
- Why the Earth has a magnetic feild.
Ø Hand out homework and explain directions.
Ø Students may start homework if time permits
Assessment-
- Complete homework handout on Magnetic stripping.
Activity Materials-
Ø Overhead
Ø Iron shavings
Ø Paper
Ø water in a jar
Ø 14 bar magnets
Resources for Lesson
Ø Article
Ø Activity handout
Ø Homework handout KEY